Paracryptodira
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Paracryptodira
__NOTOC__ Paracryptodira is an extinct group of reptiles in the clade Testudinata (which contains modern turtles and their extinct relatives), known from the Jurassic to Paleogene of North America and Europe. Initially treated as a suborder sister taxon, sister to Cryptodira,Gaffney (1975) they were then thought to be a very primitive lineage inside the Cryptodira according to the most common use of the latter taxon.Joyce (2007) They are now often regarded as late-diverging stem group, stem-turtles, lying outside the clade formed by Cryptodira and Pleurodira. Paracryptodires are divided into three main groups, Compsemydidae, known from the Late Jurassic to Paleocene of North America and Europe, Pleurosternidae, known from the Late Jurassic to Early Cretaceous of North America and Europe, and Baenidae, known from the Early Cretaceous to Eocene of North America. The latter two groups are more closely related to each other than to ''Compsemys'', forming the clade Baenoidea. Characte ...
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Compsemydidae
Compsemydidae is an extinct family of Testudinata, turtles, likely belonging to the clade Paracryptodira. The earliest undisputed member is ''Tongemys'' from the Berriasian age of the Early Cretaceous; two Late Jurassic genera (''Riodevemys'' and ''Selenemys'') have also sometimes been included in the group, but may alternatively be members of the family Pleurosternidae. The genus ''Compsemys'' survived the Cretaceous–Paleogene extinction event and lasted until the Thanetian age of the Paleocene. Taxonomy Compsemydidae was named in a 2015 paper by Pérez-García ''et al.'', who included the type genus ''Compsemys'' and its possible synonym ''Berruchelus''. A 2020 paper by Joyce and Rollot expanded the family to include the enigmatic ''Peltochelys'' from the Early Cretaceous, as well as the Late Jurassic ''Riodevemys'' and ''Selenemys'' that had earlier been placed in Pleurosternidae. A 2021 paper by Rollot ''et al.'' added the Late Cretaceous ''Kallokibotion'' to the family, b ...
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Helochelydridae
The Helochelydridae are an extinct family of stem-turtles known from fossils found in North America and Europe spanning the Early to Late Cretaceous. Description The skull, shell and osteoderms of helochelydrids are covered in small, cylindrical protuberances, which are a distinctive characteristic of the group. They are thought to be terrestrial, based on the presence of limb osteoderms (granicones) and bone histology. Their skull morphology is dissimilar to that of extant tortoises, suggesting an omnivorous habit similar to that of box turtles. Taxonomy Helochelydridae includes all turtles that are more closely related to '' Helochelydra'' than '' Sichuanchelys'', '' Meiolania'', or extant turtles. Although referred to as Solemydidae in recent literature on extinct turtles, Helochelydridae has priority over Solemydidae. They are placed as part of the clade Perichelydia. Some recent studies have recovered them as paracryptodires, though other studies have found them to be ...
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Pleurosternidae
Pleurosternidae is an extinct family of freshwater turtles belonging to Paracryptodira. They are definitively known from the Late Jurassic to Early Cretaceous (Albian) of Western Europe and North America. Genera Valid taxa *'' Dinochelys'' Morrison Formation, United States, Late Jurassic (Tithonian) *''Dorsetochelys'' Purbeck Group, England, Early Cretaceous (Berriasian) Bückeberg Formation, Germany, Berriasian *''Glyptops'' Morrison Formation, United States, Late Jurassic (Tithonian) *''Pleurosternon'' Purbeck Group, England, Early Cretaceous (Berriasian), Ágreda locality, Spain, Tithonian-Berriasian, France, Tithonian-Berriasian *''Riodevemys'' Villar del Arzobispo Formation, Spain, Late Jurassic (Tithonian) *''Selenemys'' Lourinhã Formation, Portugal, Late Jurassic (Kimmeridgian) *''Toremys'' Escucha Formation, Spain, Early Cretaceous (Albian The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic col ...
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Glyptops
''Glyptops'' is an extinct genus of pleurosternid freshwater turtle known from the Late Jurassic of North America. Taxonomy The type species, ''Glyptops plicatulus'', was first described as ''Compsemys plicatulus'' by Edward Drinker Cope on the basis of AMNH 6099, a partial shell from the Late Jurassic (Tithonian) aged Morrison Formation of Colorado. In 1890, a partial skull, YPM 1784 (described from Como Bluff, Wyoming), was named ''Glyptops ornatus'' by Othniel Charles Marsh. Later, Oliver Perry Hay recognized ''Compsemys plicatulus'' and ''Glyptops ornatus'' as being from the same species, hence the new combination ''G. plicatulus''. Another Morrison species of ''Glyptops'', ''G. utahensis'', was described from a complete shell (CM 3412) found at Dinosaur National Monument in Utah. ''Glyptops'' later became a wastebasket taxon to refer to isolated shell fragments with a finely sculpted surface texture. The type of ''Glyptops plicatulus'' was later judged to be a ''nomen d ...
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Dorsetochelys
''Dorsetochelys'' is an extinct genus of turtle from the Early Cretaceous of southern England and northwestern Germany. Taxonomy The type species, ''Dorsetochelys delairi'', was described on the basis of DORCM G.23, a complete skull from the Early Cretaceous (Berriasian) Purbeck Group of Dorset, England. Later, a turtle skull from the vicinity of Como Bluff, Wyoming, was described as a new species, ''D. buzzops'', in honor of Buzz Pitman, a museum director of the Rock River Museum near Como Bluff. However, a cladistic analysis conducted in 2013 recovered that species as a member of Baenidae, sister to '' Uluops''. In 2012, pleurosternid remains were described from the Early Cretaceous (Berriasian) Bückeberg Formation of Lower Saxony Lower Saxony is a States of Germany, German state (') in Northern Germany, northwestern Germany. It is the second-largest state by land area, with , and fourth-largest in population (8 million in 2021) among the 16 ' of the Germany, Federal R ...
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Baenidae
Baenidae is an extinct family of paracryptodiran turtles known from the Early Cretaceous to Eocene of North America. While during the Early Cretaceous they are found across North America, during the Late Cretaceous they are only found in Laramidia, having disappeared from Appalachia. The majority of lineages survived the K-Pg Extinction, but the family was extinct by the latest Eocene. The name of the type genus, '' Baena,'' appears to be of Native American origin, likely from the Arapaho ''be’enoo''. They are primarily found in freshwater deposits, and are considered to be aquatic, with a largely generalist habit. Genera * †'' Arundelemys'' * †'' Arvinachelys'' * †'' Baena'' * †'' Cedrobaena'' * †'' Chisternon'' * †'' Edowa'' * †'' Gamerabaena'' * †'' Gehennachelys'' * †'' Hayemys'' * †''Lakotemys'' Lakota Formation, Berriasian-Valanginian In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between ...
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Forest Marble Formation
The Forest Marble is a geological formation in England. Part of the Great Oolite Group, it dates to the late Bathonian stage of the Middle Jurassic.Weishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 538–541. . Lithology The primary lithology of the formation typically consists of greenish grey variably calcareous silicate mudstone, with lenticular cross bedded limestone units deposited in a marine setting. Paleobiota Despite the formation being nearly entirely marine, at several localities abundant remains of terrestrial microvertebrates are found, the primary locality being the Kirtlington Mammal Bed (designated 3p) in Kirtlington Quarry near Kirtlington, Oxfordshire. Another important locality is Watton Cliff near Eype in Dorset. Fish Dinosaurs Ornithischians Saurischians Amphi ...
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Turtle
Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked turtles), which differ in the way the head retracts. There are 360 living and recently extinct species of turtles, including land-dwelling tortoises and freshwater terrapins. They are found on most continents, some islands and, in the case of sea turtles, much of the ocean. Like other Amniote, amniotes (reptiles, birds, and mammals) they breathe air and do not lay eggs underwater, although many species live in or around water. Turtle shells are made mostly of bone; the upper part is the domed Turtle shell#Carapace, carapace, while the underside is the flatter plastron or belly-plate. Its outer surface is covered in scale (anatomy), scales made of keratin, the material of hair, horns, and claws. The carapace bones deve ...
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Glyptops Pervicax
''Glyptops'' is an extinct genus of pleurosternid freshwater turtle known from the Late Jurassic of North America. Taxonomy The type species, ''Glyptops plicatulus'', was first described as ''Compsemys plicatulus'' by Edward Drinker Cope on the basis of AMNH 6099, a partial shell from the Late Jurassic (Tithonian) aged Morrison Formation of Colorado. In 1890, a partial skull, YPM 1784 (described from Como Bluff, Wyoming), was named ''Glyptops ornatus'' by Othniel Charles Marsh. Later, Oliver Perry Hay recognized ''Compsemys plicatulus'' and ''Glyptops ornatus'' as being from the same species, hence the new combination ''G. plicatulus''. Another Morrison species of ''Glyptops'', ''G. utahensis'', was described from a complete shell (CM 3412) found at Dinosaur National Monument in Utah. ''Glyptops'' later became a wastebasket taxon to refer to isolated shell fragments with a finely sculpted surface texture. The type of ''Glyptops plicatulus'' was later judged to be a ''nomen dubium ...
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Uluops
''Uluops'' is an extinct genus of paracryptodire turtle from the Late Jurassic (Tithonian) of North America. The type and only species is ''Uluops uluops'', which is known from a single skull from the Morrison Formation The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltston .... See also * Paleobiota of the Morrison Formation References Further reading *K. Carpenter and R. T. Bakker. 1990. A new latest Jurassic vertebrate fauna, from the highest levels of the Morrison Formation at Como Bluff, Wyoming, with comments on Morrison biochronology. Part II. A new baenid turtle. Hunteria 2(6):3-4 Pleurosternidae Prehistoric turtle genera Tithonian genera Late Jurassic turtles Late Jurassic reptiles of North America Morrison fauna Fossil taxa described in 1990 Taxa named by Kennet ...
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Chisternon
''Chisternon'' is a genus of baenid turtles from the Eocene of North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri .... References *''The Osteology of the Reptiles'' by Alfred Sherwood Romer External links''Chisternon''in the Paleobiology Database Baenidae Prehistoric turtle genera Eocene turtles Eocene reptiles of North America Fossil taxa described in 1872 Taxa named by Joseph Leidy {{paleo-turtle-stub ...
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